My Wi-Fi won't work...?

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Hello!! I'm new to the forums and I have a question.
I have an Optimus Boston (I'm not sure if it was sold anywhere else than Portugal, but it works like any Android phone), and since about two weeks ago its Wi-Fi just spontaneously stopped working. It won't detect any networks, it won't show any ones I had saved, and it turns off by itself after about 10-20 seconds of "trying" to look for networks.
I tried turning off the phone, changing settings on the Advanced section, changing the phone card, searching online for solutions... But it won't work. It just won't. Can someone help me
(General)

My wife and I both have 2014 Moto Xs on AT&T, roughly 3 weeks old.
My phone is 100% great, however her phone will only connect to Wifi networks if mobile data is turned off.
I've tried everything, and can't get it to work correctly.